What i mean is if you can change the letters we can change the cell itself.
And then controle what the cell does. (like help function another part of our body.) Once scientist can do that then the possibilities to the human body are almost endless.

Well, remember that each different type of cell in the body has EXACTLY the same DNA compososition.

Differences between a cardiac muscle cell and pituitary gland cell .. has to do with the fact that a different set of genes is expressed in one tissue versus the other. it is not because the DNA composition of each cell type is any different.

Thus, it wouldn't be necessary to alter the genetic code to change a cell itself.. you just have to change what DNA is actually transcribed and translated into protein. (cuz different cell types also express different proteins... the proteins are what makes a endocrine cell..and endocrine cell)

The other HUGE problem is that DNA is Highly highly highly conserved between organism. THis is a result of evolution "choosing" genetic compositions that are most-compatible with life. SO, changing DNA sequences is EXTREMELY tricky... and 1 nucleotide changes can be the difference between life and death.

HOwever!!! if scientist were to have abetter understanding of transcriptional control.. they'd be more able to manipulate cells.. by changing which genes are expressed versus repressed.

well, if you just transplanted a cell... sometimes it would live.. sometimes it wouldn't function normally... but in many situations it would die.

however, if you know the gene that were responsible for making a particular protein... you can insert a "foreign" gene into a cell ... and if done under all of the correct conditions your cell will express the protein from the DNA you inserted.